In order to obtain desired delivery performance, a medical elongated body such as a catheter is structured to include an inner layer, an outer layer covering the outside of the inner layer, and a reinforcement body that is provided between the inner layer and the outer layer. This type of medical elongated body is manufactured by forming the inner layer, the reinforcement body, and the outer layer sequentially from an axial center to the outside in a radial direction, and suitably performing processes (cutting, shaping, attachment of configuration components, and the like) in the middle of the formation. The reinforcement body is generally formed of reinforcement wires which are metallic wires.
For example, JP-A-2008-167826 discloses a manufacturing method of cutting a stacked cylindrical body in which an inner layer and a reinforcement body are formed, attaching a ring-shaped contrast marker thereto, and thereafter, coating the stacked cylindrical body with an outer layer. According to this manufacturing method, it is possible to prevent the coming apart of multiple reinforcement wires of the reinforcement body by melting and integrating the inner layer and the reinforcement body together via heating of the reinforcement body when cutting the stacked cylindrical body.
As means for preventing the coming apart of the reinforcement wires when the reinforcement body is cut, there is a method of annealing (annealing process) the reinforcement body in addition to the method disclosed in JP-A-2008-167826. Since it is possible to eliminate stress of the reinforcement wires of the reinforcement body according to this method, it is possible to prevent the jumping of the reinforcement wires even if the reinforcement body is cut. For this reason, the inner layer and the reinforcement body can be well coated with the outer layer.
In a case where an annealing process is performed on a medical elongated body, since heat is transferred to an inner layer from a reinforcement body, unintended spots of the inner layer may melt or burn. In some cases, a defect occurs, for example, a portion of the inner layer of the medical elongated body gets a hole, and the reinforcement body is exposed. Particularly, the inner layer of the medical elongated body is desirably made of thermoplastic resin which can be easily molded into a desired shape and be manufactured at low cost. In contrast, since this type of material has a low melting point, the material may melt simply due to the annealing process.
The disclosure here is made to solve that problem, and to provide a method of manufacturing a medical elongated body by which it is possible to simply prevent the melting of an inner layer even if a reinforcement body is heated, and thus, it is possible to manufacture medical elongated bodies at a high yield.